Microburet



Dec. M), 194,6,

P. A. SHAFFER, JR 2,412,295

MICROBURET Filed Aug. '7, 1944 INVENIOA PML/P A Smyrne-@ Patented Dec. 10,

UNITED STATES PATENT] 2,412,295

Mlcltonvltrz'r y Pump A. snuffel-Jr., nsadenacaungassignerio I California Institute Research Foundation.` Pasadena, Calif.,y a corporation of lApplicatie. August v 1944, sesamo. 548,323

10mm. `(c1.222-26 My invention relates `to microburets vand among the objects of my invention are:

First, to provide a microburet which makes possible accurate measurement of liquids used'in titration procedures and is particularly adapted for use in conjunction with the analysis of extremely small samples such as used in microchemical procedures.

Second, to provide a. microburet which interchangeably receives and operates glass syringes containing the various liquids used for titration.

Third, to provide a microburet which, though` accurately controlling the movement of the plunger into the cylinder of a glass syringe. places no side thrust on .the plunger so that the plunger y moves freely.

Fourth, .to provide a microburet which is compact and easily operated.

With the above and other objects in view which `may appear hereinafter, reference ,fis directed to the accompanying drawing in which:

Figure 1 is a front view of the microburet showing a syringe in position. Y

fFigure 2 isa side elevational view of the microburet.

Figure 3 is a fragmentary longitudinal sectional view thereoi taken through 3-3 of Figure 1.

Figure 4 is a top view of themicroburet.

Figurev5 is a transverse sectionalview `thereof taken through 5 5 of Figure 2 with the slide bracket removed.

Figure 6 is a transverse sectional view .through 8 6 of Figure 2 showing the barrel and under side of the traveler member. y

Figure 'I is a transverse sectional view through 'I--l of Figure 3.

'A tubular barrel I is closed at its lower end by a. plug 2. The upper end of the barrel I receives ball bearings aand 4. y The lower ball ybearing 3 rests on a shoulder 5 Within the barrel. A bushing B screw threads into the upper end of the barrel I and engages the upper bearing 4.`

The bearings 3 and 4 t the stem portion I of a drive screw 8. The lower bearing is press fitted on the stem portion 'I'and abuts a shoulder 9. Slight clearance is provided between the inner race of .the bearing 4 and the stem portion. The

` upper end of the stem portion receives a head or knob I0 for the purpose of rotating the drive screw. The head I0 includes a cylindrical portion bearing a micrometer scale which coacts with a. reference line inscribed on lthe barrel I at its upper end.

The tubular barrel I forms a guide means which receives a traveler member II. The travladapted vto be compressed bya tensionscrewl so that slack due to the thread clearancebetween the traveler member II kand drive `s crew vmay be taken up. In addition, the traveler Vis provided with one or more longitudinal slitsI4 ltojform segmental portions which may be spreadslightly so that the traveler member I I hasnoininal frictional engagement with the walls of ythebarrel I. One side of the barrel I isk provided with Aa longitudinal slot I5. A lateral stem I6 yissefcilred in the .traveler member II and protrudes through the slot I5. The lateral stem'fits into a socket formed 1n slide bracket I1. The end of the slide bracket adjacent the barrel is curved intof'vconformity therewith and the slideA bracket' is secured to the stem I6 by a set screw IBL", One vertical side of the slide bracket I'I is 'inscribed with a reference marking which coacts witha micrometer scale disposed longitudinally on the barrel I. Theunder side of the slide bracketfisprovided with a ball bearing I9 in order vto `form"afheinispherical projection. This bears against tlieph'ead P-I of a plunger P forming part of a syringes.

vThe upper corners of the vslide"bracket `are ible but are strong enough 'to rsisethe'plunger' in the cylinder C of the syringe` l, 1 ,l Secured to the "lower side portion of the barrel I is a V-block 2B.` The V-block is providedlwith a V-shaped groove adapted .toz accommodate -the cylinder of the'syringe and alnerit `withthe .ball bearing I9. Clamp arms 21` formed fof spring material are secured to the Sides'ofthebarrel I and extend laterally along .the sides 'y "on/fthe V-block. vTheir extremitlesfare inturned to gripl the cylinder C and hold itinthe yV-groovebff'l'wo pairs of clamp yarms are provided'. yThe V-block and clamp arms thus form a holder for the'cylinder C of the syringe. Each pair of clamp arms is connected by a screw 28 which extends through a hole formed in the V-block 26. One end of each screw is riveted or otherwise secured to one of .thepair of clamp arms and the other or extended end of each screw receives a nut 29. f holder attached to said guide member; and scale 'Ihe upper end of the cylinder Cv is provided with a ange C-I which rests against .the upper end of the V-block so that when the cylinder is clamped it remains in place as the plunger is moved downwardly therein. The clamp arrns` 21' are suillciently stifl' to hold the cylinder against drawn.

upward movement when the plunger. is with- The barrel'is provided with a mounting stem V30y by. which the microburet may be lsecured in a suitable fitting cammed by a'ring stand or similarI .sugport customarily used for chemical apparatus.-

Byreason of the micrometer scales provided" on the" head lo anden .the barrel l the extent of.

movement of the plunger in its cylinder kmay be accurately determined. v

The ball bearing and spring clip engagement'v between the slide bracket Hand the plunger P\ avoids the application of *side thrustv on the plunger. This is highly desirable for leven a moderate sidevthrust will cause .the plunger to bind inthe cylinder dueto the snugiluid type.

tit which is maintained between these two members. A

The syringe per se is conventional and inasmuch as they are lreadily inserted and-removed from .the V-block and slidel bracket several syringes containing different liquids used in titration procedures may be used interchangeably, and 1the syringes may be inserted and removed s'everal times as needed before their contents are discharged. r

The various changes and altem-ate arrangements may be made within the scope of the appended claims, in which it is my intention to claim all novelty inherent in the invention as broadly as the prior art permits.

I claim:

111A microburet comprising: a'syringe includj ing'a cylinder and a plunger movable therein and provided with a head at its outer end; a tubular member having a slot in its side wall; a syringe cylinder mounting means on said tubular member below said slot for positioning said syringe cylinder in .offset parallel relation to said tubular member; a micrometer screw journaled within said .tubular member; a traveler member threaded l on said screw within said tubular member; and a syringe plunger engaging bracket disposedA externailyoi said tubular member and attached to said traveler member through said slot.

2. The combination with asyringecylrider and plunger of a microburetk comprising: va, traveler guide member; means secured onv said guide member for removably receiving a syringe cylinder; a traveler slidable on said guide member and including means for gripping the head' o1' a syringe plunger; a screw for moving said traveler; a first micrometer scale incorporated with said screw and guide member; and a second micrometer scale incorporated with saidtraveler and guide 4 member; a syringe plunger engaging bracket connected to said screw member; a syringe cylinder means for measuring the extent of movement of said traveler andsyringe plunger.

4. The combination with a syringe having a cylinderv 'and plunger, -of a microburet comprising: a tubular guide member; a traveler member guided within said. guide member; a screw mem- -ber for moving said traveler member; a syringe plunger engaging bracket connected tosaid screw member; a syringe cylinder holder attached to saidV guide member; and scale means for measuring end of said projection; a V-blo'cksecuredto said barrelbelow said sliding bracket; yieldable clamp elements on opposite sides of 'sind V`block.

for holding the cylinder of a syringe,v against said V-block; and yieldable clips pivotally mounted on said sliding bracket and having arms" adapted 4to `engage the head of said plunger, wherebyjm'o'vement of said sliding bracket correspondingly moves said plunger in saidcylinder. f

y6. In a microburet for metering discharge of iluid from'a glass syringe wherein the syringe'includes a cylinder and plunger therefor, having a head at its extended end, the combination of: a .tubular barrel; a drive screw rotatably. mounted in said fbarrelya travelergfor said drive screw equipped with a lateral `projection,'there being' an accommodating longitudinal slot in said barrel; a sliding bracket secured tothe protruding end of said projection; a pairl of clips pivotally mounted on said bracket and having arms "adapted to engage the head of said syringe and hold said head against the under side of said bracket; and means for clamping they cylinder of said ysyringe to the side of said barrel in alinement with said plunger. i ,y j, l

7. In a microburet for metering discharge'fof iiuidyfrom a glass syringe wherein the syringe includes a cylinder and plunger therefor, having a head at its extended end, the combination fof:

. a tubularbarrel; a drive screw rotatably mounted member, whereby movement of said traveler and I syringe plunger maybe measured.

3. The combination with a syringe having a cylinder and plunger, of a microburet comprislng: a guide member; a traveler member guided thereby; a screw member for moving vsaid traveler in said barrel; a traveler for said Vdrive screw equipped with a lateral projection, vthere being an accommodating longitudinal y.slot in said barrel; a sliding bracket secured .to therprotruding end of said projection; .a pair of clips pivotally mounted on said bracket and having arms adapted to engage the headof saidsyringeand hold said head against the u-nder side of said bracket; means for clamping the cylinder of saidbsyringe to lthe side of said barrel in alinementlith said plunger; a handle for said drive screw mounted at one end of said barrel; and micrometer scales for measuring movement of4 said handle and'said sliding bracket relative to said barrel. Y

. PHILIP A. sHAFFEnun. 

